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Objective: To compare the transcutaneous oxygen pressure (tcpO2) measurement values and changes in compressed areas of surgical patients before and after surgery and to explore the related factors influencing the tcpO2 changes before and after surgery., Methods: Researchers selected 100 patients who underwent elective surgery in a tertiary comprehensive hospital from November 2021 to September 2022. A self-designed general information questionnaire was used to collect patient general information and disease-related data, including gender, age, smoking and drinking history, hypertension, diabetes, local skin temperature and humidity, related biochemical indicators, and activities of daily living score. Researchers used a transcutaneous oxygen pressure meter to measure and record the tcpO2 of the compressed areas (sacrococcygeal area, scapula area, and heel area) before and after surgery., Results: Among the 100 patients, 37.00 % (37/100) developed type I/II pressure ulcers after surgery, and 30 patients (81.08 %) showed regression within 2 h after surgery. There was no statistically significant difference in the preoperative tcpO2 measurement values of the scapula and heel areas between the group with and without pressure ulcers, but the preoperative tcpO2 measurement value of the sacrococcygeal area in the group without pressure ulcers was higher than that in the group with pressure ulcers (P < 0.01). The factors affecting the preoperative tcpO2 measurement value of the sacrococcygeal area were smoking and surgical type. After surgery, the tcpO2 measurement values of the three areas in the group with pressure ulcers were significantly lower than those in the group without pressure ulcers (P < 0.01). Comparing the tcpO2 values of different areas, it was found that the tcpO2 value was lowest in the sacrococcygeal area, followed by the heel area, and the tcpO2 value in the scapula area was highest both before and after surgery (P < 0.01). The main factors affecting the postoperative tcpO2 measurement value were diabetes, Glassgow score, surgical time, and intraoperative red blood cell transfusion., Conclusion: The measurement of tcpO2 is related to the incidence of surgically acquired pressure ulcers, and this technology may become an important tool for quantitative assessment of the risk of pressure ulcers., Competing Interests: Declaration of competing interest The authors declare no conflict of interest in preparing this article., (Copyright © 2024 Tissue Viability Society / Society of Tissue Viability. Published by Elsevier Ltd. All rights reserved.)

The vascular causes of lower-extremity ulcers cannot be neglected because they can directly affect treatment methods. No detailed epidemiological statistics have described vascular etiological diagnosis in China. This study aimed to explore the prevalence of clinical vascular etiological examination of lower-extremity ulcers and improve the diagnosis and treatment effectiveness of lower-extremity ulcers. Data were collected from the WoundCareLog database, which includes 2413 cases of lower-extremity ulcers from 478 hospitals nationwide. Data analysis revealed that 1698 (70.4%) lower-extremity blood flow examinations (including physical examination [PE] and assistant examinations [AE]) were performed, of which 61.7% were PE, 10.4% were AE only, and 27.9% were the combined PE and AE[PAE]. The proportion of nonexaminations was higher in the nondiabetic group than in the diabetic group (χ 2 = 34.5; P < .01). The positive rates of vascular etiological examination in the diabetic and nondiabetic groups were 69.7% and 70.7%, respectively. Among the four economic regions of China, there were statistically significant differences in the use of the different examination methods. The examination of vascular diseases in lower-extremity ulcers in China has not been fully popularized and requires improvement; there was no statistically significant difference between examination rates by doctors and nurses, which is mainly based on PE. However, PE has certain rates of misdiagnosis and missed diagnosis. The false-positive and false-negative rates were 25.7% and 57.6%, respectively. The use of an AE can compensate for this deficiency by making diagnosis more precise, while the quantitative diagnostic criteria allow disease diagnosis to transcend geographical and operator differences and maximize uniformity. The vascular B-ultrasound examination is more suitable for the medical environment in China because of its mature technology, high hospital penetration rate, and low cost., (© 2020 by the Wound Healing Society.)

Introduction: Hyperoxemia in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) leads to adverse outcomes. It remains prevalent in the pre-hospital Emergency Medical Services (EMS) and Emergency Department (ED)., Objective: To determine the key predictors for hyperoxemia in AECOPD in EMS and ED., Methods: This was a prospective observational study of AECOPD patients in EMS and two EDs. Hyperoxemia was defined as PaO 2 > 65 mm Hg (corresponds to SpO 2 > 92%). We determined apriori candidate factors in Patient, Organization and Staff domains. Primary outcomes were the key predictors for hyperoxemia. Secondary outcomes were in-hospital mortality and mechanical ventilation rates in hyperoxemic versus non-hyperoxemic groups. We generated a logistic regression model for each domain. We reported the adjusted odds ratios (AORs), 95% CIs and p values. We selected the output factors using AOR ≥2.0 and ≥2.5 for modifiable and non-modifiable factors, respectively. These selected factors were fed into a final model with eventual factors selected based on: threshold AORs as stated above and/or 95% CIs including these AORs., Results: Three hundred and twenty-six patients were analysed; 60.7% had hyperoxemia. We found three eventual modifiable factors; first, ED SpO 2 > 95% [AOR 2.62 (95% CIs: 1.61-4.33); P < 0.001], EMS non-rebreathing mask [AOR 2.01 (95% CIs: 1.06-3.97); P = 0.04]; and ED nasal cannula [AOR 1.69 (95% CIs: 1.05-2.72); P = 0.03]. Secondary outcomes did not differ between groups., Conclusion: We identified three key modifiable predictors. We intend to conduct an interventional study using them to reduce hyperoxemia rate in AECOPD., (© 2019 John Wiley & Sons Ltd.)

Background: Widespread use of transcutaneous P CO 2 (P tcCO 2 ) monitoring is currently limited by concerns many practitioners have regarding accuracy. We compared the accuracy of P tcCO 2 with that of P aCO 2 measurements in critically ill children, and we investigated whether clinical conditions associated with low cardiac output or increased subcutaneous tissue affect this accuracy., Methods: We performed a single-center prospective study of critically ill children placed on transcutaneous monitoring., Results: There were 184 children enrolled with paired P aCO 2 and P tcCO 2 values. Subjects had a median age of 31.8 mo (interquartile range 3.5-123.3 mo). Most children were mechanically ventilated ( n = 161, 87.5%), and many had cardiac disease ( n = 76, 41.3%). The median P aCO 2 was 44 mm Hg (interquartile range 39-51 mm Hg). The mean bias between P aCO 2 and P tcCO 2 was 0.6 mm Hg with 95% limits of agreement from -13.6 to 14.7 mm Hg. The P tcCO 2 and P aCO 2 were within ±5 mm Hg in 126 (68.5%) measurements. In multivariable modeling, cyanotic heart disease (odds ratio 3.5, 95% CI 1.2-10, P = .02) and monitor number 2 (odds ratio 3.8 95% CI 1.3-10.5, P = .01) remained associated with P tcCO 2 ≥ 5 mm Hg higher than P aCO 2 . Serum lactate, fluid balance, renal failure, obesity, vasoactive-inotrope score, and acyanotic heart disease were not associated with high or low P tcCO 2 values. In 130 children with a second paired P tcCO 2 and P aCO 2 measurement, predicting the second measured P aCO 2 by subtracting the initial observed difference between the P tcCO 2 and P aCO 2 from the subsequent measured P tcCO 2 decreased the mean bias between observed and predicted P aCO 2 to 0.2 mm Hg and the 95% limits of agreement to -9.4 to 9.7 mm Hg., Conclusions: P tcCO 2 provides an acceptable estimate of P aCO 2 in many critically ill children, including those with clinical conditions that may be associated with low cardiac output or increased subcutaneous tissue, although it does not perform as well in children with cyanotic heart disease. P tcCO 2 may be a useful adjunct monitoring method, but it cannot reliably replace P aCO 2 measurement., (Copyright © 2019 by Daedalus Enterprises.)

Background: Transcutaneous monitors are utilized to monitor a patient's respiratory status. Some patients have similar values when comparing transcutaneous carbon dioxide (P tcCO 2 ) values with blood gas analysis, whereas others show extreme variability. A retrospective review of data was performed to determine how accurately P tcCO 2 correlated with CO 2 values obtained by arterial blood gas (ABG) or capillary blood gas., Methods: To determine whether P tcCO 2 values correlated with ABG or capillary blood gas values, subjects' records were retrospectively reviewed. Data collected included the P tcCO 2 value at the time of blood gas procurement and the ABG or capillary blood gas P CO 2 value. Agreement of pairs of methods (ABG vs P tcCO 2 and capillary blood gas vs P tcCO 2 ) was assessed with the Bland-Altman approach with limits of agreement estimated with a mixed model to account for serial measurements per subject., Results: A total of 912 pairs of ABG/P tcCO 2 values on 54 subjects and 307 pairs of capillary blood gas/P tcCO 2 values on 34 subjects were analyzed. The P CO 2 range for ABG was 24-106 mm Hg, and P tcCO 2 values were 27-133 mm Hg. The P CO 2 range for capillary blood gas was 29-108 mm Hg, and P tcCO 2 values were 30-103 mm Hg. For ABG/P tcCO 2 comparisons, the Pearson correlation coefficient was 0.82, 95% CI was 0.80-0.84, and P was <.001. For capillary blood gas/P tcCO 2 comparisons, the Pearson correlation coefficient was 0.77, 95% CI was 0.72-0.81, and P was <.001. For ABG/P tcCO 2 , the estimated difference ± SD was -6.79 ± 7.62 mm Hg, and limits of agreement were -22.03 to 8.45. For capillary blood gas/P tcCO 2 , the estimated difference ± SD was -1.61 ± 7.64 mm Hg, and limits of agreement were -16.88 to 13.66. The repeatability coefficient was about 30 mm Hg., Conclusions: Based on these data, capillary blood gas comparisons showed less variation and a slightly lower correlation with P tcCO 2 than did ABG comparisons. After accounting for serial measurements per patient, due to the wide limits of agreement and poor repeatability, the utility of relying on P tcCO 2 readings for this purpose is questionable., Competing Interests: The authors have disclosed no conflicts of interest., (Copyright © 2018 by Daedalus Enterprises.)

Objective: To investigate the effect of alveolar recruitment combined with surfactant administration on children with acute respiratory distress syndrome (ARDS)., Material and Methods: A prospective, randomized, controlled and sequential study was carried out. Group A (16 children) was treated with both the alveolar recruitment manoeuvres (ARM) and the administration of the surfactant every 8 h for 3 days; group B (15) received the usual treatment only. The alveolar recruitment was carried out by increasing positive end-expiratory pressure 2 by 2 cm H 2 O to improve the transcutaneous oxygen saturation values up to 88% and 90%. Demographic data, gasometric and ventilator parameters, chest radiography and 28-day mortality were evaluated., Results: There were no significant differences in baseline characteristics between groups. An hour after treatment, significant differences (P < 0.001) were observed in transcutaneous oxygen saturation (SaO 2 ; Group A: 94.1%, Group B: 89.9%), PaO 2 /FiO 2 (212.7 and 126.4) and oxygenation index (OI; 11.4 and 18.5). After 8 h, the differences in SaO 2 (Group A: 94.6%, Group B: 90.3%), PaO 2 /FiO 2 (225.8 and 126.9) and OI (10.8 and 18.4) were also significant (P < 0.001). From the fifth dose of the surfactant, the static compliance (P = 0.0034) and radiological images (P = 0.002) were more greatly improved in group A than in group B. Survival was significantly higher in group A (81.3%) than in group B (26.7%) (P = 0.006)., Conclusions: The combined treatment of surfactant administration and ARM resulted in a better oxygenation and survival in children with ARDS than when only recruitment was used., (© 2016 John Wiley & Sons Ltd.)

Background: Transcutaneous carbon dioxide (P(tcCO2)) monitoring is being used increasingly to assess acute respiratory failure. However, there are conflicting findings concerning its reliability when evaluating patients with high levels of P(aCO2). Our study evaluates the accuracy of this method in subjects with respiratory failure according to the severity of hypercapnia., Methods: We included subjects with respiratory failure, admitted to a respiratory intermediate care unit, who required arterial blood gas analysis. Simultaneously, P(tcCO2) was measured using a digital monitor. Relations between P(aCO2) and P(tcCO2) were assessed by the Pearson correlation coefficient. Bland-Altman analysis was used to test data dispersion, and an analysis of variance test was used to compare the differences between P(aCO2) and the corresponding P(tcCO2) at different levels (level 1, <50 mm Hg; level 2, 50-60 mm Hg; level 3, >60 mm Hg)., Results: Eighty-one subjects were analyzed. The main diagnosis was COPD exacerbation (45%). P(tcCO2) correlated well with P(aCO2) (r2 = 0.93, P < .001). Bland-Altman analysis showed a mean P(aCO2) - P(tcCO2) difference of 4.9 ± 4.4 with 95% limits of agreement ranging from -3.6 to 13.4. The difference between variables increased in line with P(aCO2) severity: level 1, 1.7 ± 3.2 mm Hg; level 2, 3.7 ± 2.8; level 3, 6.8 ± 4.7 (analysis of variance, P < .001)., Conclusions: Our study showed an acceptable agreement of P(tcCO2) monitoring with arterial blood gas analysis. However, we should consider that P(tcCO2) underestimates P(aCO2) levels, and its accuracy depends on the level of hypercapnia, so this method would not be suitable for acute patients with severe hypercapnia., (Copyright © 2016 by Daedalus Enterprises.)

Background: To survey the current practice of monitoring and management of severe traumatic brain injury (TBI) patients in the critical care units across the United Kingdom., Methods: A structured telephone interview was conducted with senior medical or nursing staff of all the adult neurocritical care units. Thirty-one neurocritical care units that managed adult patients with severe TBI were identified from the Risk Adjustment in Neurocritical Care (RAIN) study and the Society of British Neurological Surgeons., Results: Intracranial pressure (ICP) monitoring was used in all the 31 institutions. Cerebral perfusion pressure was used in 30 of the 31 units and a Cerebral perfusion pressure target of 60 to 70 mm Hg was the most widely used target (25 of 31 units). Transcranial Doppler was used in 12 units (39%); brain tissue oxygen (PbtO(2)) was used in 8 (26%); cerebral microdialysis was used in 4 (13%); jugular bulb oximetry in 1 unit; and near-infrared spectrometry was not used in any unit. Continuous capnometry was used in 28 (91%) units for mechanically ventilated patients. Mannitol was the most commonly used agent for osmotherapy to treat intracranial hypertension., Conclusions: We identified that there was no clear consensus and considerable variation in practice in the management of TBI patients in UK neurocritical care units. A protocol-based management has been shown to improve outcome in sepsis patients. Given the magnitude of the problem, we conclude that there is an urgent need for international consensus guidelines for management of TBI patients in critical care units.

Background: Prediction of the return of spontaneous circulation (ROSC) in cardiac arrest patients is a parameter for deciding when to stop cardiopulmonary resuscitation (CPR) or to start extracorporeal CPR. We investigated the change in transcutaneous PCO2 (PtcCO2) in cardiac arrest patients., Methods: This study was carried out as a retrospective chart review. Patients with out-of-hospital cardiac arrest or in-hospital cardiac arrest within the emergency department were included. PtcCO2 monitoring with a V-Sign™ combined monitor (SenTec Inc., Therwil, Switzerland) was applied to patients at the start of CPR. We divided the included patients into the ROSC group and the no ROSC group. The ROSC group was subdivided into those achieving ROSC <15 min CPR and >15 min CPR. The change in the PtcCO2 value was analyzed at 0 min, 5 min, 10 min, and 15 min from PtcCO2 stabilization and was compared among the groups., Results: A total of 42 patients were enrolled. Twenty-eight patients achieved ROSC; 13 patients achieved ROSC <15 min CPR and 15 patients achieved ROSC >15 min CPR. Fourteen patients expired without ROSC. The absolute values of PtcCO2 was lower in the ROSC group than in the no ROCS group. The PtcCO2 change over time had a tendency to decrease or to remain constant in the ROSC groups. In contrast, all patients in the no ROSC group experienced an increase in the PtcCO2 change during CPR except one case., Conclusions: PtcCO2 monitoring provides non-invasive, continuous, and useful monitoring in cardiac arrest patients.

The Department of Health is promoting the generation of specialist networks to manage long term ventilatory weaning and domiciliary non-invasive ventilation patients. Currently the availability of these services in England is not known. We performed a short survey to establish the prevalence of sleep and ventilation diagnostic and treatment services. The survey focussed on diagnostic services and Home Mechanical Ventilation (HMV) provision, and was divided into (a) availability of diagnostics, (b) funding, and (c) patient groups. This survey has confirmed that the majority of Home Mechanical Ventilation set-ups are currently for Obesity Related Respiratory Failure and Chronic Obstructive Pulmonary Disease. We have found that there is variable provision of diagnostic services, with the majority of units offering overnight oximetry (95%) but only 55% of responders providing a home mechanical ventilation service. Even more interestingly, less than two thirds of units charged their primary care trust for this service. These data may assist in the development of regional networks and specialist home mechanical ventilation centres.

Objective: To determine the validity of transcutaneous oximetry (TcPO(2)) as a predictor of lower limb amputation healing complications., Design: A systematic review and meta-analysis., Methods: We searched five major medical databases, relevant review articles and reference lists and included all studies that evaluated TcPO(2) for its ability to predict lower limb amputation healing failure. We selected eligible articles and conducted data abstraction independently and in duplicate., Results: Thirty-one studies, enrolling 1824 patients with 1960 amputations, met our inclusion criteria. Only one study reported undertaking a multivariable analysis, which demonstrated that a TcPO(2) level below 20 mmHg was an independent predictor of re-amputation occurrence (adjusted odds ratio (OR) 3.08, 95% confidence interval (CI) 1.19-7.98). Fourteen prospective cohort studies reported data that allowed for the calculation of an unadjusted relative risk of lower limb amputation healing complications leading to amputation revision associated with a TcPO(2) level below cut-offs of 10 mmHg (1.80; 95% CI 1.19-2.72), 20 mmHg (1.75; 95% CI 1.27-2.40) 30 mmHg (1.41; 95% CI 1.22-1.62) and 40 mmHg (1.24; 95% CI 1.13-1.39)., Conclusions: This review suggests that TcPO(2) predicts healing complications of lower limb amputations. A value of less than 40 mmHg results in a 24% increased risk of healing complication compared to over 40 mmHg and the risk further increases as the TcPO(2) decreases. There is, however, insufficient evidence to judge whether this tool adds important information beyond clinical data or to suggest an optimal threshold value. There is a need for a large, sufficiently powered study that adjusts for appropriate clinical variables., (Copyright © 2011 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.)

Objective: To analyse the quality of the prescription of home oxygen therapy (OT) in a health area of Murcia., Methods: A prospective study of 125 patients in a respiratory therapy clinic, evaluated with a questionnaire and blood-gas analysis while breathing ambient air. Related respiratory therapy was also assessedin COPD and asthma patients., Results: We studied 125 cases in the 3 months following the prescription of home oxygen therapy in 72 men (58%) and 53 women (42%) with a mean age of 77.2 ± 11.6. The most common type of home OT prescribed was for palliative cases in 45 patients (36%), followed by COPD in 42 (33.6%). In 88 (92%) of the 96 medical reports that we evaluated, insufficient data as to how to administer oxygen were available. Twenty-five percent of home OT prescriptions were given without blood-gas analyses, and in the 65 cases with a blood-gas analysis only 11 (17%) met oxygen value criteria for home OT as per regulations. Oxygen desaturation was not present in 31% of the palliative care home OT cases. The analysis of blood-gases during the clinic visit in non-palliative care cases demonstrated that 61% did not meet the blood-gas criteria to continue on home OT. Eighty percent of COPD and asthma patients on home OT did not receive the correct respiratory therapy., Conclusions: Quality problems in the prescription of home OT exist in our area. Palliative care is the principal reason for home OT prescriptions. In COPD and asthma patients who receive home OT, related respiratory therapy is not ideal., (Copyright © 2010 SECA. Published by Elsevier Espana. All rights reserved.)

The purpose of the study was to examine whether changes in pCO(2) mediate changes in fear of bodily sensation (as indexed by anxiety sensitivity) in a bio-behavioral treatment for panic disorder that targets changes in end-tidal pCO(2). Thirty-five panic patients underwent 4 weeks of capnometry-assisted breathing training targeting respiratory dysregulation. Longitudinal mediation analyses of the changes in fear of bodily symptoms over time demonstrated that pCO(2), but not respiration rate, was a partial mediator of the changes in anxiety sensitivity. Results were supported by cross lag panel analyses, which indicated that earlier pCO(2) levels predicted later levels of anxiety sensitivity, but not vice versa. PCO(2) changes also led to changes in respiration rate, questioning the importance of respiration rate in breathing training. The results provide little support for changes in fear of bodily sensations leading to changes in respiration, but rather suggest that breathing training targeting pCO(2) reduced fear of bodily sensations in panic disorder.

Monitoring cerebral oxygenation with near infrared spectroscopy may identify periods of cerebral desaturation and thereby the patients at risk for perioperative neurocognitive issues. Data regarding the performance of near infrared spectroscopy monitoring during deep hypothermic circulatory arrest are limited. The current study presents data regarding use of a commercially available near infrared spectroscopy monitor during deep hypothermic circulatory arrest in paediatric patients undergoing surgery for congenital heart disease. The cohort included 8 patients, 2 weeks to 6 months of age, who required deep hypothermic circulatory arrest for repair of congenital heart disease. The baseline cerebral oxygenation was 63 +/- 11% and increased to 88 +/- 7% after 15 min of cooling to a nasopharyngeal temperature of 17-18 degrees C on cardiopulmonary bypass. In 5 of 8 patients, the cerebral oxygenation value had achieved its peak value (either >or=90% or no change during the last 2-3 min of cooling on cardiopulmonary bypass). In the remaining 3 patients, additional time on cardiopulmonary bypass was required to achieve a maximum cerebral oxygenation value. The duration of deep hypothermic circulatory arrest varied from 36 to 61 min (43.4 +/- 8 min). After the onset of deep hypothermic circulatory arrest, there was an incremental decrease in cerebral oxygenation to a low value of 53 +/- 11%. The greatest decrease occurred during the initial 5 min of deep hypothermic circulatory arrest (9 +/- 3%). Over the entire period of deep hypothermic circulatory arrest, there was an average decrease in the cerebral oxygenation value of 0.9% per min (range of 0.5 to 1.6% decline per minute). During cardiopulmonary bypass, cooling and deep hypothermic circulatory arrest, near infrared spectroscopy monitoring followed the clinically expected parameters. Such monitoring may be useful to identify patients who have not achieved the highest possible cerebral oxygenation value despite 15 min of cooling on cardiopulmonary bypass. Future studies are needed to define the cerebral oxygenation value at which neurological damage occurs and if interventions to correct the decreased cerebral oxygenation will improve perioperative outcomes.

We developed a three-wavelength time-resolved spectroscopy (TRS) system, which allows quantitative measurement of hemodynamics within relatively large living tissue. We clinically evaluated this TRS system by monitoring cerebral circulation during cardiopulmonary bypass surgery. Oxyhemoglobin, deoxyhemoglobin, total hemoglobin and oxygen saturation (SO(2)) were determined by TRS on the left forehead attached with an optode spacing of 4 cm. We also simultaneously monitored jugular venous oxygen saturation (SjvO(2)) and arterial blood hematocrit (Hct) using conventional methods. The validity and usefulness of the TRS system were assessed by comparing parameters obtained with the TRS and conventional methods. Although the changes in SO(2) were lower than those in SjvO(2), SO(2) obtained by TRS paralleled the fluctuations in SjvO(2), and a good correlation between these values was observed. The only exceptions occurred during the perfusion period. Moreover, there was a good correlation between tHb and Hct values (r(2)=0.63). We concluded that time-resolved spectroscopy reflected the conditions of cerebral hemodynamics of patients during surgical operations.

Objective: The aim of this study was to validate the V-Sign digital sensor (SenTec AG, Therweil, Switzerland) for combined noninvasive assessment of pulse oxymetric oxygen saturation (SpO(2)) and transcutaneous carbon dioxide tension (PtcCO(2)) in adults after cardiac surgery., Methods: In twenty one patients, aged 51-86 years, simultaneous measurements of blood gases with the V-Sign Sensor and with two Nellcor Durasensors (model DS-100A), one at the opposite earlobe and one with a finger clip, were compared first during hyper-, normo- and hypocapnia and at different pulse rates using a pacemaker, and then at 2-h intervals up to 8 h. Agreement was assessed by Bland-Altman analysis., Results: PtcCO(2) data of three patients were excluded because of calibration failure of the device. Median (range) PtcCO(2) for the remaining patients was 5.49 (3.3-7.6) kPa and arterial carbon dioxide tension (PaCO(2)) was 5.43 (3.61-7.41) kPa. Corresponding mean bias was +0.05 kPa and limits of agreement (LOA) were -1.2/+1.3 kPa. During normo- and hypoventilation, mean bias was good at +0.02 and +0.04 kPa respectively, but limits of agreement were poor at -0.67/+0.69 and -0.81/+0.88 kPa. In 10 patients, an initial overshoot of PtcCO(2 )was observed. Mean bias of SpO(2) and pulse rate was close to zero (-1.5% and +0.001 bpm respectively), but limits of agreement were unacceptably high (-21.4/+18.4% and -22.3/+22.3 bpm)., Conclusions: In the present state of development the SenTeC Digital monitor V-Sign device has serious limitations. Additional efforts are necessary to eliminate calibration failures and the initial overshoot of PtcCO(2) as well as to improve detection of SpO(2) and pulse rate.

An association between asthma and bronchial hyperresponsiveness (BHR) has been demonstrated. It is possible that the relationship between asthma severity and BHR in children with asthma is different in infants and in adolescents. The aim of this study is therefore to evaluate the effect of aging on the relationship between the severity of asthma and BHR in children with asthma. We measured BHR in 386 subjects ranging from 2 to 20 years of age. The subjects consisted of 323 children with asthma (boys:girls = 193:130, mean age 9.7 years) and 63 age-matched controls (boys:girls = 25:38, mean age 8.2 years). BHR was measured using the methacholine inhalation challenge by measuring the transcutaneous oxygen pressure (tcPO2) in children less than 6 years of age (Dmin-PO2) and by measuring the respiratory resistance (Rrs) in children 6 years of age and older (Dmin-Rrs). Throughout the whole age range, both the Dmin-PO2 and Dmin-Rrs in each asthma severity group were higher than those in the controls. In the asthmatics aged 2-5 years, the Dmin-PO2 levels in the mild asthma group were higher than those in the moderate and severe asthma groups (p < 0.001, p < 0.001, respectively), and the Dmin-PO2 levels in the moderate asthma group were also higher than those in the severe asthma group. This tendency was also found in the age ranges of 6-9 years and 10-13 years. In the asthmatics aged 14-20 years, the Dmin-Rrs levels were not significantly different among the three groups. Taken together, these data show that aging has an effect on the relationship between the severity of asthma and BHR during childhood and that BHR may not be the sole determinant for the severity of asthma in adolescence.

Objective: The present study assessed the validity of approximate entropy (ApEn) analysis of arterial oxygen saturation (SaO(2)) data obtained from pulse oximetric recordings as a diagnostic test for obstructive sleep apnea (OSA) in patients clinically suspected of suffering this disease., Methodology: A sample of 187 referred outpatients, clinically suspected of having OSA, was studied using nocturnal pulse oximetric recording performed simultaneously with complete polysomnography. ApEn analysis was applied to SaO(2) data., Results: Patients with OSA presented significantly higher approximate entropy levels than those without OSA (1.08+/-0.30 versus 0.47+/-0.26). Apnea-hypopnea index was correlated significantly with ApEn (r=0.607; p<0.001). Using receiver operating characteristic curve analysis, we obtained a diagnostic sensitivity of 88.3% and specificity of 82.9%, positive predictive value of 88.3% and a negative predictive value of 82.9%, at a threshold of 0.679. As a diagnostic test, this method presents high sensitivity and specificity compared to traditional methods in the diagnosis of OSA., Conclusion: We conclude that ApEn analysis of SaO(2) data obtained from pulse oximetric recordings could be useful as a diagnostic technique for OSA subjects.

Objectives: To determine the effectiveness and safety of procedural sedation and analgesia (PSA) in a Canadian community emergency department (ED) staffed primarily by family physicians and to assess the role of capnometry monitoring in PSA., Methods: One hundred and sixty (160) consecutive procedural sedation cases were reviewed from the ED of a rural hospital in Huntsville, Ont. The ED is mainly staffed by family physicians who have received in-house training in PSA. Safety and effectiveness measures were extrapolated from a standardized PSA form by a blinded research assistant., Results: The mean age of the patient population was 33.6 years (standard deviation = 23.6). Fifty-four percent of the patients were male, and 33% of the cases were pediatric. PSA medications included propofol (84%), fentanyl (51%) and midazolam (15%), and the procedural success rate was 95.6%. The adverse event (AE) rate was 18% and included apnea (10%), inadequate sedation (3%), bradycardia (2%), desaturation (1%), hypotension (1%) and bag-valve-mask use (1%). In those aged > or = 65 years there was a greater incidence of apnea. There were no episodes of emesis and there were no intubations. A modified jaw thrust manoeuvre was used in 23% of the cases. I the 64% of cases where capnometry was used, there was no association between its use and any AE measures., Conclusion: Procedural sedation was safe and effective in our environment. Capnometry recording did not appear to alter outcomes, although the data are incomplete.

Background: PCO2 and PO2 are important monitoring parameters in neonatal intensive care units (NICU). Compared to conventional blood gas measurements that cause significant blood loss in preterms, transcutaneous (tc) measurements allow continuous, non-invasive monitoring of blood gas levels. The aim of the study was to survey the usage and opinions among German speaking NICUs concerning tc blood gas monitoring., Methods: A questionnaire was developed and sent to 56 head nurses of different NICUs in Germany, Switzerland and Austria., Results: A completely answered questionnaire was obtained from 41 NICUs. In two of these units tc measurements are not performed. In most NICUs (77%), both PtcO2 and PtcCO2 are measured simultaneously. Most units change the sensors every 3 hours; however, the recommended temperature of 44 degrees C is used in only 15% of units. In only 8% of units are arterial blood gases obtained to validate tc values. Large variations were found concerning the targeted level of oxygen saturation [median upper limit: 95% (range 80-100%); median lower limit: 86% (range 75-93%)] and PO2 [median upper limit: 70 mmHg (range 45-90 mmHg); median lower limit: 44 mmHg (range 30-60 mmHg)]., Conclusion: Our survey shows that the use of tc monitors remains widespread among German speaking NICUs, despite earlier data suggesting that their use had been abandoned in many NICUs worldwide. In addition, we suggest that the current method of monitoring oxygenation may not prevent hyperoxemia in preterm infants.

The CAS neonatal NIRS system determines absolute regional brain tissue oxygen saturation (SnO2) and brain true venous oxygen saturation (SnvO2) non-invasively. Since NIRS-interrogated tissue contains both arterial and venous blood from arterioles, venules, and capillaries, SnO2 is a mixed oxygen saturation parameter, having values between arterial oxygen saturation (SaO2) and cerebral venous oxygen saturation (SvO2). To determine a reference for SnO2, the relative contribution of SvO2 to SaO2 drawn from a brain venous site vs. systemic SaO2 is approximately 70:30 (SvO2:SaO2). If the relationship of the relative average contribution of SvO2 and SaO2 is known and does not change to a large degree, then NIRS true venous oxygen saturation, SnvO2, can be determined non-invasively using SnO2 along with SaO2 from a pulse oximeter.

We investigated the prevalence and characteristics of intrapulmonary shunt using contrast echocardiography with harmonic imaging in 130 liver transplant candidates. We found a high prevalence of intrapulmonary shunts and a significant correlation between the degree of intrapulmonary shunt and the Child-Pugh classification score.

Objective: Our aim was to evaluate the utility of transcutaneous CO2 (TC-CO2) monitoring in following the response to therapy in children and adolescents in diabetic ketoacidosis (DKA) requiring ICU admission., Methods: During therapy for DKA, TC-CO2 was monitored and compared with the serum bicarbonate values (HCO3-). As clinically indicated, serum electrolytes including serum HCO3- were drawn and at the same time, the TC-CO2 value was recorded. Using the TC-CO2 value and the equation (PaCO2=1.5xHCO3-+8), a calculated HCO3- value was determined. The measured serum HCO3- value was subtracted from the calculated HCO3- value and the absolute difference was recorded. The difference between the measured serum HCO3- and the calculated HCO3- was analysed using analysis of variance after stratification for serum HCO3- values and patient age ranges. Calculated to serum HCO3- values were compared using linear regression analysis. In addition, serum HCO3- values were plotted against TC-CO2 values to derive an equation from these data which would relate the TC-CO2 values to the measured serum HCO3-., Results: The cohort included 28 patients ranging in age from 1.6 to 21 years (9.4 +/- 4.7 years) and in weight from 13 to 96 kg (35.6 +/- 18.2 kg). Two additional patients were not included as the initial TC-CO2 values were inaccurate because of tissue hypoperfusion. In the remaining 28 patients, the absolute difference between the calculated bicarbonate and serum bicarbonate values was 1.5 +/- 1.2 mmol.l-1. The difference was < or =2 mol.l in 74.4% of samples and < or=5 mmol.l(-1) in 99.2%. No difference in the value between the calculated and measured serum HCO3- was present according to serum HCO3- value or patient's age. Linear regression analysis of calculated HCO3- against serum HCO3- revealed a slope of 0.95 and an r2 value of 0.88. Linear regression analysis using serum HCO3- against TC-CO2 resulted in the following equations: TC-CO2=(1.64xHCO3-)+3.9 or HCO3-=0.61x(TC-CO2-3.9)., Conclusions: TC-CO2 correlates with serum HCO3- and can be used to follow therapy in children and adolescents in DKA.

Objective: To compare endtidal and transcutaneous respiratory monitoring of high-frequency jet ventilation (HFJV) in rigid bronchoscopy. Both techniques provide a noninvasive measurement of pCO2., Methods: High-frequency jet ventilation was applied via a rigid bronchoscope. Driving pressure (DP) was initially adapted to ensure normal ventilation. It was then changed twice by +/- 30% from the initial value. Endtidal and transcutaneous data were compared with arterial blood gas monitoring (ABG)., Results: Results were analyzed separately for the time just after changing the driving pressure (10 min) and the remaining time until the next change of the driving pressure (4 min). The first part was called the dynamic phase, and the second part the steady-state phase. Correlation coefficient between endtidal capnography and ABG was 0.96 for the steady state and 0.94 for the dynamic phase, respectively. Bland-Altman analysis revealed a bias of -0.21 kPa with limits of agreement (LOA) 1.63 kPa for the steady state and -0.25 kPa, 2.08 kPa for the dynamic phase, respectively. Correlation coefficient between transcutaneous monitoring and ABG for the steady state phase was 0.83, and was 0.72 for the dynamic phase. Bland-Altman analysis resulted in a bias of -0.89 kPa with LOA - 3.84 kPa during steady state and 0.92 kPa, 4.06 kPa for the dynamic phase, respectively., Conclusion: Endtidal capnography offers accurate respiratory monitoring of HFJV. Transcutaneous monitoring showed a good correlation to ABG only during steady-state conditions. For the dynamic phase the accuracy was significantly lower. Thus, we cannot recommend transcutaneous respiratory monitoring for the specific indication of rigid bronchoscopy using HFJV.

Transcutaneous blood gas (TCBG) analysis is a noninvasive alternative method of estimation of blood gas tensions. The objective of the study reported here was to validate this method against standard blood gas (STBG) analysis in adult and juvenile Sprague-Dawley rats. We sought to establish the optimal TCBG probe site and temperature, to establish probe temperatures that would not cause thermal burns, to evaluate correlations between blood gas values (PaCO2 and PaO2) determined by use of TCBG and STBG, and to evaluate the sensitivity of the TCBG unit to changes in arterial blood gas partial pressures. Our results indicated that: in general, the xyphoid area was the optimal site for probe placement, with 44.5 degrees C being the optimal probe temperature for the highest correlation, but thermal burns may be a problem; probe temperatures of 42.5 degrees C (adults) and 42.0 degrees C (juveniles) do not cause thermal burns when left in place for three hours; probe temperatures of 44 degrees C (adults) and 42 degrees C (juveniles) resulted in moderate correlation between PaCO2 and PtcCO2; and the TCBG unit adequately responded to changes in arterial blood gas partial pressures. Neither PtcCO2 or PtcO2 reflect actual values of PaCO2 or PaO2, respectively. We concluded that TCBG analysis may be used as an indicator of change in PaCO2 with sufficient animal numbers under tightly controlled conditions, but not as an indicator of change in PaO2 in adult and juvenile rats.

Calciphylaxis is a severe complication of chronic renal failure, confined almost exclusively to patients on dialysis therapy. Histological characteristics of calciphylaxis include small-vessel calcifications of skin, subcutaneous tissue, and visceral organs. These vascular changes promote tissue ischemia that often results in tissue necrosis. In this study, we investigated the extent of skin ischemia in patients with calciphylaxis by means of transcutaneous oxygen tension (TCPO(2)) measurement, a noninvasive test that accurately assesses skin oxygenation. TCPO(2) levels were measured in 21 patients with calciphylaxis and 21 age- and sex-matched patients without evidence of calciphylaxis (controls). TCPO(2) levels were measured bilaterally at the chest, anterior abdomen, and upper thigh while patients breathed room air and after a 30-minute exposure to 100% fraction of inspired oxygen (FIO(2)). Compared with controls, patients with calciphylaxis showed significantly lower TCPO(2) levels at each body region. In both controls and patients with calciphylaxis, lower TCPO(2) levels correlated with increased weight and use of hemodialysis. No correlation with serum parathyroid hormone (PTH), serum calcium, or serum phosphorus values was present, although 39% of the patients with calciphylaxis had markedly elevated PTH values (sixfold greater than normal; >300 pg/dL). Low TCPO(2) levels in patients with calciphylaxis were documented in body regions with and without skin lesions. In patients with calciphylaxis, extremely low TCPO(2) values (

To help in determining management strategy as an alternative to amputation by using a synthetic prostacycline, a preliminary study was undertaken in 12 patients (11 men and one woman), with a mean age of 71.08 years, ie, 13 limbs evaluated at the stage of amputation. All patients were treated with a combination of iloprost and physical therapy (massage, specific exercises, cardiorespiratory training). Static transcutaneous oxygen pressure (TcPO2) was measured, with a sensitization test by verticalization and inhalation of oxygen, on day (D) D0, D15, D28, D60, D180, and D365. Results were analyzed in absolute terms and by tissue oxygenation ratio (TOR) (ratio between absolute values of TcPO2 in the foot and those of a reference chest electrode). Supine TOR and vertical TOR, with values of 36.67 and 65.08, respectively, appeared to be significantly linked to the variable "preservation of limb". At 1 year, seven limbs were preserved (53.85%) while amputation had been scheduled for all the patients treated. Evidence was found in all patients who kept their limb of stability (7.69%) and a decrease in (30.77%) or disappearance of pain (15.38%) at 1 year.

Using time-resolved spectroscopy, we have developed an experimental approach to obtain the absolute changes in concentration in the scattering medium of living tissues. The time-resolved Beer-Lambert equation can be applied to living tissue due to the fact that the optical attenuation by absorption can be separated from that by scattering, and the intensity of the light along the non-linear scattered optical path is exponentially attenuated by the absorption. Based on the above, the absolute concentration of haemoglobin as well as oxygen saturation in the rat head can be determined in situ under various respiratory conditions where multiwavelength measurements were performed. The optically assessed values agree with those determined directly by the gas analysis of our previous report. The present method is very simple and therefore opens up wide applications for time-resolved spectrophotometry in clinical medicine as a technique for quantitative near-infrared oxygen monitoring.

The authors performed a retrospective study on a data base of 525 patients with peripheral arterial disease, to analyze the pathophysiologic meaning of resting transcutaneous pressure of carbon dioxide (PCO2) and of CO2 production during three minutes of local ischemia. The resting and postischemic PCO2 and its maximum increase related to rest (PCO2 production) were measured with Kontron 7640 equipment. The results show a significant increase of PCO2 production in the Fontaine stage 2A (183 patients, 4.61 mmHg, P < 0.0001), in stage 2B (194 patients, 5.22 mmHg, P < 0.0001), in the third stage (83 patients, 6.10 mmHg, P < 0.0001), and in the fourth stage (53 patients, 8.66 mmHg, P < 0.0001). Only the patients at the first stage showed an insignificant increase, perhaps because of the small number (12) in this group. The authors feel that the measurement of tcPCO2 production during local ischemic stress can be a very important parameter for evaluating peripheral arterial disease as an expression of metabolic tissue performance and, overall, of the tissue resistance to ischemia.

Exercise influences blood flow distribution and may thereby influence tissue oxygen. Given that experimental evidence suggests exercise improves wound healing, this study was undertaken to determine the effect of exercise on subcutaneous tissue oxygen tension (PscO2). Subjects performed a treadmill test to maximum oxygen consumption (VO2) while PscO2 and subcutaneous temperature (Tsc) were measured using a tonometer and optode/thermocouple system. There were no significant differences in PscO2 between measurement points. Mean Tsc had increased 4.8% at maximum VO2, and 6.3% as the cool-down period ended and differed significantly across the exercise period. Changes in PscO2 and Tsc were not correlated. Oxygen availability was neither enhanced nor significantly reduced by exercise. However, PscO2 did not increase as expected in relation to increases in Tsc. Further study will determine the purported beneficial effects of exercise and the mechanism by which it may affect wound healing.

Background: Few studies have compared sensitivities of ankle-to-brachial index (ABI) and transcutaneous oxygen tension (TcPO2) in a large group of patients with Leriche stage II intermittent claudication., Method and Results: 111 patients (138 limbs) with a stable chronic (> three months) intermittent claudication and significant peripheral vascular disease (PVD) proved by angiography were studied. They performed a treadmill test (10%, 3 km/hr) limited by limb pain. ABI and TcPO2 were measured before, just after exercise, and after three and ten minutes of recovery in supine position. Sensitivities per patient for ABI and TcPO2 were respectively at rest: 82.9% and 28.8%, and after exercise: 88.3% and 62.2%. Sensitivities per leg (n = 138) for ABI and TcPO2 were respectively at rest: 73.9% and 26.8%, and after exercise: 82.6% and 34%. The sensitivity of TcPO2 increased to 56.5% after three minutes of recovery but was always less than that of ABI, which was maximal just after exercise (82.6%). The sensitivity of the regional perfusion index was similar to that of TcPO2. The sensitivity of TcPO2 increased with respect to the Leriche stage and the number of lesions but was always lower than that of ABI. There was a weak correlation between TcPO2 and ABI after exercise, but no correlation was noted between maximal walking distance, ABI, and TcPO2., Conclusion: TcPO2 is not required in patients with Leriche stage II intermittent claudication but might be useful either in severely affected patients (Leriche stage III or IV) or in selected patients.

9 pulse oximeters (BIOX-III, Nellcor 250, Jaeger CNS, Micro2), Pulsox-8, Oxycount, PulsOXImeter, PalcoLabs and Pulsox-7) were studied in 90 COPD patients. The transcutaneus oxygen saturation (SaO2%) was compared with arterial oxygen saturation calculated simultaneously with drawn blood samples (AVL-995). The measurement of error distribution and the cumulative distribution function (CDF) of measurement errors allows ranking of the pulse oximeters, which can be divided in 3 groups. We conclude that the accuracy of the tested nine pulse oximeter does not enable precise absolute measurements, specially at lower oxygen saturation ranges.

We assessed (1) the sensitivity and specificity of exercise oxygen saturation measurement (EOS) for the diagnosis of Pneumocystis carinii pneumonia (PCP); and (2) the cost of introducing this indirect diagnostic test compared with that of standard diagnostic strategies for PCP. In a prospective study, 85 HIV-infected patients with suspected PCP underwent EOS, followed by induced sputum (IS) and bronchoalveolar lavage (BAL) if IS was negative for P. carinii. The prevalence of PCP was 0.22, the sensitivity of IS was 0.6, and its specificity was perfect. The cost ratios of IS to BAL and EOS to BAL were 0.1 and 0.2, respectively. A desaturation of three points was the best cutoff point, giving perfect sensitivity and a specificity of 0.77. The cost analysis showed that the introduction of EOS into diagnostic strategies for PCP is highly justified when the local prevalence is low. Exercise oxygen saturation measurement is simple and safe, and the results are available rapidly; its sensitivity is perfect and its specificity good. Its economic utility depends on its cost and the local prevalence of PCP in the test population.

Transcutaneous oximetry is gaining worldwide acceptance as a simple and effective means of evaluating the cutaneous circulation. Oximetry involves the use of Clark-type electrically heated oxygen-sensing electrodes that are attached to the skin; various protocols for the performance of studies (utilizing exercise, oxygen inhalation, leg elevation, and various other maneuvers) have been developed which may improve the accuracy when used in certain settings. Applications for transcutaneous oximetry are found in areas such as: (1) diagnosis of disease, (2) quantification of disease severity, (3) prediction of healing potential for skin ulcers or amputation sites, (4) assessment of microvascular disease, and (5) determination of cutaneous vasomotor status. Transcutaneous oxygen tension serves as an index of the adequacy of skin blood flow, and therefore yields valuable "functional" information not provided by noninvasive "anatomical" testing modalities such as echo-doppler ultrasound imaging.

In the evaluation of any medical technology the efficacy, effectiveness, and efficiency must each be considered before routine deployment is recommended. Since the widespread practice of patient monitoring by pulse oximetry and capnography has occurred before the performance of rigorously controlled trials, definitive proof of worth is lacking. The purpose of this review is to appraise critically the effectiveness of this technology. The assessment was performed using concepts developed in epidemiology and community medicine to establish a given factor to be causative to a given outcome. The current literature pertaining to anaesthetic adverse outcomes was reviewed, and the use of monitors evaluated against the criteria of a causal relationship. While the conclusions are based more on the absence of positive data (owing to low frequency of adverse anaesthetic occurrences) rather than negative results, it must be concluded that the effectiveness of such monitoring has yet to be demonstrated. Such a conclusion should not detract from their use, for the role of an individual factor in the complex chain of accident evolution will seldom be demonstrable. Rather, such an appraisal should encourage a clear perspective of the depth of our clinical science, and encourage more rigorous critical evaluation in the future.